**HP 75C** **Program Collection**

Merry Christmas everyone! I hope everyone is safe, happy, and blessed.

**LAWCOS: Law of Cosines**

335 bytes

**100 DISP "Law of Cosines" @ WAIT .25**

**105 OPTION ANGLE DEGREES**

**180 DISP "Î˜ is opp. side a" @ WAIT .25**

**110 INPUT "1) Side, 2) Angle? "; H**

**115 ON H GOTO 1000, 2000**

**1000 INPUT "b?, c?, Î˜? "; B,C,T**

**1010 A=SQR(B^2+C^2-2*B*C*COS(T))**

**1020 DISP "a: "; STR$(A) @ END**

**2000 INPUT "a?, b?, c? "; A,B,C**

**2010 T=ACOS((B^2+C^2-A^2)/(2*B*C))**

**2020 DISP "Î˜:"; STR$(T); "°" @ END**

Example:

1) Side: 1

B = 11.78, C = 32.12, T = 60

Result: a = 28.1440793063

2) Angle: 2

A = 14.55, B = 12.65, C = 17.00

Result: Î˜ = 56.5108780171°

**SPECPOLY: Special Polynomials**

526 bytes (10/27/2022)

1.Cheb: Chebyshev Polynomial of the 1st order

2.Herm: Hermite Polynomial

3.Lagur: Laguerre Polynomial (with Î±=0)

4.Legen: Legendre Polynomial of the 1st Order

**100 DISP "Polynomials: Type?" @ WAIT .5**

**105 INPUT "1.Cheb 2.Herm 3.Lagur 4.Legen:"; H**

**110 INPUT "x? "; X**

**115 INPUT "order? ";N**

**120 A=1 @ B=X*(H=1 OR H=4)+2*X*(H=2)+(1-X)*(H=3)**

**300 IF N=0 THEN DISP A @ END**

**302 IF N=1 THEN DISP B @ END**

**305 FOR I=2 TO N**

**310 ON H GOSUB 500,505,510,515**

**315 A=B**

**320 B=C**

**325 NEXT I**

**330 DISP C**

**335 END**

**500 C=2*X*B-A @ RETURN**

**505 C=2*X*B-2*(I-1)*A @ RETURN**

**510 C=((2*(I-1)+1-X)*B-(I-1)*A)/I @ RETURN**

**515 C=((2*I-1)*X*B-(I-1)*A)/I @ RETURN**

Source:

Davidson, James J. "Chebyshev Polynomials, First & Second Kind, Tn(x) & Un(x)", "Hermite Polynomials, H(n); n≥n", "Laguerre Polynomials, Generalized, Ln^(Î±)(x)", "Legendre Functions, First & Second Kinds, Pn(x) & Qn(x)" ENTER 65 NOTES Vol. 3 No. 8 September 1976 pp. 11-12

Examples:

x = 11, order = 6

1. Cheb: 55989361

2. Herm: 106439224

3. Lagur: -35.5902777778

4. Legen: 25289461

**ENGINE: Automotive Engine Mathematics**

630 bytes (10/27/2022)

**100 DISP "Engine Math" @ WAIT .5**

**110 INPUT "# cylinders? "; N**

**120 DISP "Solve for?" @ WAIT .25**

**125 INPUT "1)DSP, 2)STROKE, 3)BORE "; H**

**130 IF H#1 THEN INPUT "DSP? "; D**

**135 IF H#2 THEN INPUT "STROKE? "; S**

**140 IF H#3 THEN INPUT "BORE? "; B**

**145 IF H=1 THEN LET D=PI/4*B^2*S*N**

**150 IF H=2 THEN LET S=D/(PI/4*B^2*N)**

**155 IF H=3 THEN LET B=SQR(D/(PI/4*S*N))**

**160 DISP "DPS= "; D @ STOP**

**165 DISP "STORKE= "; S @ STOP**

**170 DISP "BORE= "; B @ STOP**

**205 INPUT "RPM? (y/n) "; I$**

**210 IF UPRC(I$)="N" THEN 400**

**300 INPUT "RPM? "; R**

**310 P=S*R/6**

**320 E=R*D*.85/3456**

**350 DISP "Piston Speed="; P @ STOP**

**360 DISP "St. Carb CFM= "; E @ STOP**

**370 INPUT "Again? (y/n) "; I$ **

**375 IF UPRC(I$)="Y" THEN 300**

**400 DISP "Done."**

Source:

Lawlor, John. __Auto Math Handbook. Calculations, Formulas, Equations, and Theory for Automotive Enthusiasts__. HP Books: Berkeley Publishing Group: New York, NY. 1991. ISBN 1-55788-020-4

**LINREG: Linear Regression**

568 bytes (10/31/2022)

**100 DISP "y=mx+b" @ WAIT .5**

**110 S0=0 @ S1=0 @ S2=0 @ S3=0 @ S4=0 @ S5=0**

**120 DISP 'Î£+ Î£- Calc'**

**130 K$=KEY$ @ IF K$='' THEN 130**

**140 IF K$="+" THEN H=1 @ GOTO 200**

**150 IF K$="-" THEN H=-1 @ GOTO 200**

**160 IF UPRC$(K$)='C' THEN 400**

**170 GOTO 130**

**200 INPUT 'x,y? '; X,Y**

**210 S0=S0+H @ S1=S1+H*X @ S2=S2+H*Y**

**220 S3=S3+H*X^2 @ S4=S4+H*Y^2 @ S5=S5+H*X*Y**

**230 DISP S0 @ WAIT .5 @ GOTO 120**

**400 B=(S5-S1*S2/S0)/(S3-S1^2/S0)**

**440 A=(S2-B*S1)/S0**

**450 R=B*SQR((S0*S3-S1^2)/(S0*S4-S2^2))**

**470 DISP 'type cont...' @ WAIT .5**

**500 DISP 'SLP=';B @ STOP**

**510 DISP 'ITC=';A @ STOP**

**520 DISP 'CORR=';R**

Instructions:

Press + to add data. Separate x and y with a comma.

Press - to delete data. Separate x and y with a comma.

Press C to determine the slope, intercept, and correlation.

Example:

Data:

5, 4.066

8, 4.125

11, 4.202

18, 4.293

21, 4.349

ITC ≈ 3.99046

SLP ≈ 0.01719

CORR ≈ 0.99376

Source:

Hewlett Packard. __HP 12C User Guide__ Edition 4. San Diego, CA 2004.

**SIMPSON: Integral Using Simpson’s Rule Approximation**

size varies - around 300 bytes

∫ FNF(X) dX from X = a to X = b

Line 100 is where you have to define your function (of X).

**100 DEF FNF(X) = [define f(x) here]**

**115 OPTION ANGLE RADIANS**

**120 INPUT "a? ";A**

**125 INPUT "b? ";B**

**130 INPUT "# parts (even)? ";N**

**135 T=FNF(A)+FNF(B)**

**140 H=(B-A)/N**

**145 FOR I TO N-1**

**150 IF FP(I/2)=0 THEN 155 ELSE 160**

**155 T=T+2*FNF(A+I*H) @ GOTO 165**

**160 T=T+4*FNF(A+I*H)**

**165 NEXT I**

**170 T=T*H/3**

**175 DISP "Integral = ";T**

Examples:

For both examples, n = 24

FNF(X)= 2*X^2+3, a = 1, b = 6, result: 158.333333333

FNF(X)=2*COS(X), a = 0, b = .785398163398, result: 1.41421357139 (exact √2)

**Happy Holidays everyone**!

Next post will be on New Years' Eve: December 31, 2022.

Eddie

All original content copyright, © 2011-2022. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.